It is the purpose of the investigation to model the antigen stimulated antibody response, concentrating in particular on modeling the thresholds inherent in this phenomenon. Using techniques from epidemiology to model the thresholds leads to a system of functional differential equations. The mathematical behavior of solutions of these equations is being investigated and a computer program is being developed to simulate the system. Comparison with experimental data is anticipated. Also of interest to the project is the applicability of optimal control theory in tolerance inducing mechanisms and the use of the catastrophe theory of Rene Thom as an alternative way to model thresholds.